The influence of hydrolysis of nylon 4 to the analysis of its water accessibility was examined by the viscosity measurement of hot water treated nylon 4 and the deuteration with hot D
2O. The results were obtained as follows. The rate constant of hydrolysis of nylon 4 assumed as the first order reaction is 1.59×10
-4 min
-1 (4×10
-6 min
-1 for nylon 6). The activation energy of hydrolysis is 17 kcal/mol (24 kcal/mol for nylon 6) and the equilibrium degree of hydrolysis, α, is 35×10
-3 (5.5×10
-3 for nylon 6) at 150°C. These results show that nylon 4 is hydrolyzed more easily than nylon 6. The influence of hydrolysis on the partition coefficient of
D between nylon 4 and D
2O aq. solution is included in the equation, where
CdD is the overall value of the partition coefficient,
CNHD,
CCOOHD and
CNH2D are partition coefficients between -NHCO-, -COOH and -NH
2 groups and D
2O solution, respectively, and
b is the number of -NHCO- linkage in the main chain. The values of
CCOOHD and
CNH2D were determined as 1.12 and 1.14, respectively, by use of succinic acid and β-alanine as model substances of terminal groups of hydrolyzed nylon 4.
It is shown that the hydrolysis gives 0.2_??_0.3% error in the observed accessibility for nylon 4 with
b=113. It is also confirmed that the deuteration does not occur by a proton transfer mechanism in nylon 4 as well as in nylon 6.
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